Lipid redistribution by α-linolenic acid-rich chia seed inhibits stearoyl-CoA desaturase-1 and induces cardiac and hepatic protection in diet-induced obese rats

Dietary Salba (Salvia hispanica L) seed rich in α-linolenic acid improves adipose tissue dysfunction and the altered skeletal muscle glucose and lipid metabolism in dyslipidemic insulin-resistant rats

This work reports the effect of dietary Salba (chia) seed rich in n-3 α-linolenic acid on the morphological and metabolic aspects involved in adipose tissue dysfunction and the mechanisms underlying the impaired glucose and lipid metabolism in the skeletal muscle of rats fed a sucrose-rich diet (SRD). Rats were fed a SRD for 3 months. Thereafter, half the rats continued with SRD while in the other half, corn oil (CO) was replaced by chia seed for 3 months (SRD+chia). In control group, corn starch replaced sucrose. The replacement of CO by chia seed in the SRD reduced adipocyte hypertrophy, cell volume and size distribution, improved lipogenic enzyme activities, lipolysis and the anti-lipolytic action of insulin. In the skeletal muscle lipid storage, glucose phosphorylation and oxidation were normalized. Chia seed reversed the impaired insulin stimulated glycogen synthase activity, glycogen, glucose-6-phosphate and GLUT-4 protein levels as well as insulin resistance and dyslipidemia.

Isolation and characterization of proteins from chia seeds (Salvia hispanica L.)

Chia ( Salvia hispanica L.) is a plant that produces seeds rich in some nutraceutical compounds with high protein content, but little is known about them; for this reason the aim of this study was to characterize the seed storage proteins. Protein fractions were extracted from chia seed flour. The main protein fraction corresponded to globulins (52%). Sedimentation coefficient studies showed that the globulin fraction contains mostly 11S and 7S proteins. The molecular sizes of all the reduced fractions were about 15-50 kDa. Electrophoretic experiments under native conditions exhibited four bands of globulins in the range of 104-628 kDa. The denaturation temperatures of crude albumins, globulins, prolamins, and glutelins were 103, 105, 85.6, and 91 °C, respectively; albumins and globulins had relatively good thermal stability. Selected globulin peptides by mass spectrometry showed homology to sesame proteins. A good balance of essential amino acids was found in the seed flour and globulins, especially of methionine+cysteine.

Docosahexaenoic acid supplementation does not improve Western diet-induced cardiomyopathy in rats

Obesity increases risk for cardiomyopathy in the absence of hypertension, diabetes or ischemia. The fatty acid milieu, modulated by diet, may modify myocardial structure and function, lending partial explanation for the array of cardiomyopathic phenotypy. We sought to identify gross, cellular and ultrastructural myocardial changes associated with Western diet intake, and subsequent modification with docosahexaenoic acid (DHA) supplementation. Wistar and Sprague-Dawley (SD) rats received 1 of 3 diets: control (CON); Western (WES); Western + DHA (WES+DHA). After 12 weeks of treatment, echocardiography was performed and myocardial adiponectin, fatty acids, collagen, area occupied by lipid and myocytes, and ultrastructure were determined. Strain effects included higher serum adiponectin in Wistar rats, and differences in myocardial fatty acid composition. Diet effects were evident in that both WES and WES+DHA feeding were associated with similarly increased left ventricular (LV) diastolic cranial wall thickness (LVW(cr/d)) and decreased diastolic internal diameter (LVID(d)), compared to CON. Unexpectedly, WES+DHA feeding was associated additionally with increased thickness of the LV cranial wall during systole (LVW(cr/s)) and the caudal wall during diastole (LVW(ca/d)) compared to CON; this was observed concomitantly with increased serum and myocardial adiponectin. Diastolic dysfunction was present in WES+DHA rats compared to both WES and CON. Myocyte cross sectional area (CSA) was greater in WES compared to CON rats. In both fat-fed groups, transmission electron microscopy (TEM) revealed myofibril degeneration, disorganized mitochondrial cristae, lipid inclusions and vacuolation. In the absence of hypertension and whole body insulin resistance, WES+DHA intake was associated with more global LV thickening and with diastolic dysfunction, compared to WES feeding alone. Myocyte hypertrophy, possibly related to subcellular injury, is an early change that may contribute to gross hypertrophy. Strain differences in adipokines and myocardial fatty acid accretion may underlie heterogeneous data from rodent studies.

The promising future of chia, Salvia hispanica L

With increasing public health awareness worldwide, demand for functional food with multiple health benefits has also increased. The use of medicinal food from folk medicine to prevent diseases such as diabetes, obesity, and cardiovascular problems is now gaining momentum among the public. Seed from Salvia hispanica L. or more commonly known as chia is a traditional food in central and southern America. Currently, it is widely consumed for various health benefits especially in maintaining healthy serum lipid level. This effect is contributed by the presence of phenolic acid and omega 3/6 oil in the chia seed. Although the presence of active ingredients in chia seed warrants its health benefits, however, the safety and efficacy of this medicinal food or natural product need to be validated by scientific research. In vivo and clinical studies on the safety and efficacy of chia seed are still limited. This paper covers the up-to-date research on the identified active ingredients, methods for oil extraction, and in vivo and human trials on the health benefit of chia seed, and its current market potential.

Tocotrienols reverse cardiovascular, metabolic and liver changes in high carbohydrate, high fat diet-fed rats

Tocotrienols have been reported to improve lipid profiles, reduce atherosclerotic lesions, decrease blood glucose and glycated haemoglobin concentrations, normalise blood pressure in vivo and inhibit adipogenesis in vitro, yet their role in the metabolic syndrome has not been investigated. In this study, we investigated the effects of palm tocotrienol-rich fraction (TRF) on high carbohydrate, high fat diet-induced metabolic, cardiovascular and liver dysfunction in rats. Rats fed a high carbohydrate, high fat diet for 16 weeks developed abdominal obesity, hypertension, impaired glucose and insulin tolerance with increased ventricular stiffness, lower systolic function and reduced liver function. TRF treatment improved ventricular function, attenuated cardiac stiffness and hypertension, and improved glucose and insulin tolerance, with reduced left ventricular collagen deposition and inflammatory cell infiltration. TRF improved liver structure and function with reduced plasma liver enzymes, inflammatory cell infiltration, fat vacuoles and balloon hepatocytes. TRF reduced plasma free fatty acid and triglyceride concentrations but only omental fat deposition was decreased in the abdomen. These results suggest that tocotrienols protect the heart and liver, and improve plasma glucose and lipid profiles with minimal changes in abdominal obesity in this model of human metabolic syndrome.

Chronic l-arginine treatment improves metabolic, cardiovascular and liver complications in diet-induced obesity in rats

l-Arginine is an important dietary amino acid in both health and disease, especially of the cardiovascular system. This study has determined whether dietary supplementation with l-arginine attenuates cardiovascular, metabolic, pancreatic and liver changes in a rat model of the human metabolic syndrome. Male Wistar rats (8-9 weeks old) were divided into four groups. Two groups of rats were fed a corn starch-rich diet (C) whereas the other two groups were given a high carbohydrate, high fat diet (H) with 25% fructose in the drinking water, for 16 weeks. One group fed each diet was supplemented with 5% l-arginine in the food for the final 8 weeks of this protocol. The corn starch diet (C) contained ∼68% carbohydrates mainly as polysaccharides, while the high-carbohydrate, high-fat diet contained ∼68% carbohydrates mainly as fructose and sucrose together with 24% fat mainly as saturated and monounsaturated fats from beef tallow. The high-carbohydrate, high-fat diet-fed rats showed the symptoms of metabolic syndrome including obesity and hypertension with heart and liver damage. Supplementation with l-arginine attenuated impairment in left ventricular and liver structure and function, glucose tolerance, and decreased blood pressure, abdominal fat pads, inflammatory cell infiltration, pancreatic cell hypertrophy and oxidative stress. This study indicates that oral supplementation with l-arginine attenuated or normalised obesity-related changes in the heart, liver and pancreas by reducing inflammation and oxidative stress associated with high carbohydrate, high fat feeding in rats.

Dietary chia seed induced changes in hepatic transcription factors and their target lipogenic and oxidative enzyme activities in dyslipidaemic insulin-resistant rats

The present study analyses the effect of dietary chia seed rich in n-3 α-linolenic acid on the mechanisms underlying dyslipidaemia and liver steatosis developed in rats fed a sucrose-rich diet (SRD) for either 3 weeks or 5 months. The key hepatic enzyme activities such as fatty acid synthase (FAS), acetyl-CoA carboxylase (ACC), glucose-6-phosphate dehydrogenase (G-6-PDH), carnitine palmitoyltransferase-1 (CPT-1) and fatty acid oxidase (FAO) involved in lipid metabolism and the protein mass levels of sterol regulatory element-binding protein-1 (SREBP-1) and PPARα were studied. (1) For 3 weeks, Wistar rats were fed either a SRD with 11 % of maize oil (MO) as dietary fat or a SRD in which chia seed replaced MO (SRD+Chia). (2) A second group of rats were fed a SRD for 3 months. Afterwards, half the rats continued with the SRD while for the other half, MO was replaced by chia for 2 months (SRD+Chia). In a control group, maize starch replaced sucrose. Liver TAG and the aforementioned parameters were analysed in all groups. The replacement of MO by chia in the SRD prevented (3 weeks) or improved/normalised (5 months) increases in dyslipidaemia, liver TAG, FAS, ACC and G-6-PDH activities, and increased FAO and CPT-1 activities. Protein levels of PPARα increased, and the increased mature form of SREBP-1 protein levels in the SRD was normalised by chia in both protocols (1 and 2). The present study provides new data regarding some key mechanisms related to the fate of hepatic fatty acid metabolism that seem to be involved in the effect of dietary chia seed in preventing and normalising/improving dyslipidaemia and liver steatosis in an insulin-resistant rat model.

An inhibitor of phospholipase A2 group IIA modulates adipocyte signaling and protects against diet-induced metabolic syndrome in rats

Obesity, type 2 diabetes, and cardiovascular disease correlate with infiltration to adipose tissue of different immune cells, with uncertain influences on metabolism. Rats were fed a diet high in carbohydrates and saturated fats to develop diet-induced obesity over 16 weeks. This nutritional overload caused overexpression and secretion of phospholipase A(2) group IIA (pla2g2a) from immune cells in adipose tissue rather than adipocytes, whereas expression of adipose-specific phospholipase A(2) (pla2g16) was unchanged. These immune cells produce prostaglandin E(2) (PGE(2)), which influences adipocyte signaling. We found that a selective inhibitor of human pla2g2a (5-(4-benzyloxyphenyl)-(4S)-(phenyl-heptanoylamino)-pentanoic acid [KH064]) attenuated secretion of PGE(2) from human immune cells stimulated with the fatty acid, palmitic acid, or with lipopolysaccharide. Oral administration of KH064 (5 mg/kg/day) to rats fed the high-carbohydrate, high-fat diet prevented the overexpression of pla2g2a and the increased macrophage infiltration and elevated PGE(2) concentrations in adipose tissue. The treatment also attenuated visceral adiposity and reversed most characteristics of metabolic syndrome, producing marked improvements in insulin sensitivity, glucose intolerance, and cardiovascular abnormalities. We suggest that pla2g2a may have a causal relationship with chronic adiposity and metabolic syndrome and that its inhibition in vivo may be a valuable new approach to treat obesity, type 2 diabetes, and metabolic dysfunction in humans.

Caffeine attenuates metabolic syndrome in diet-induced obese rats

OBJECTIVE

Caffeine is a constituent of many non-alcoholic beverages. Pharmacological actions of caffeine include the antagonism of adenosine receptors and the inhibition of phosphodiesterase activity. The A₁ adenosine receptors present on adipocytes are involved in the control of fatty acid uptake and lipolysis. In this study, the effects of caffeine were characterized in a diet-induced metabolic syndrome in rats.

METHODS

Rats were given a high-carbohydrate, high-fat diet (mainly containing fructose and beef tallow) for 16 wk. The control rats were given a corn starch diet. Treatment groups were given caffeine 0.5 g/kg of food for the last 8 wk of the 16-wk protocol. The structure and function of the heart and the liver were investigated in addition to the metabolic parameters including the plasma lipid components.

RESULTS

The high-carbohydrate, high-fat diet induced symptoms of metabolic syndrome, including obesity, dyslipidemia, impaired glucose tolerance, decreased insulin sensitivity, and increased systolic blood pressure, associated with the development of cardiovascular remodeling and non-alcoholic steatohepatitis. The treatment with caffeine in the rats fed the high-carbohydrate, high-fat diet decreased body fat and systolic blood pressure, improved glucose tolerance and insulin sensitivity, and attenuated cardiovascular and hepatic abnormalities, although the plasma lipid concentrations were further increased.

CONCLUSION

Decreased total body fat, concurrent with increased plasma lipid concentrations, reflects the lipolytic effects of caffeine in adipocytes, likely owing to the caffeine antagonism of A₁ adenosine receptors on adipocytes.

Chronic high-carbohydrate, high-fat feeding in rats induces reversible metabolic, cardiovascular, and liver changes

Age-related physiological changes develop at the same time as the increase in metabolic syndrome in humans after young adulthood. There is a paucity of data in models mimicking chronic diet-induced changes in human middle age and interventions to reverse these changes. This study measured the changes during chronic consumption of a high-carbohydrate (as cornstarch), low-fat (C) diet and a high-carbohydrate (as fructose and sucrose), high-fat (H) diet in rats for 32 wk. C diet feeding induced changes without metabolic syndrome, such as disproportionate increases in total body lean and fat mass, reduced bone mineral content, cardiovascular remodeling with increased systolic blood pressure, left ventricular and arterial stiffness, and increased plasma markers of liver injury. H diet feeding induced visceral adiposity with reduced lean mass, increased lipid infiltration in the skeletal muscle, impaired glucose and insulin tolerance, cardiovascular remodeling, hepatic steatosis, and increased infiltration of inflammatory cells in the heart and the liver. Chia seed supplementation for 24 wk attenuated most structural and functional modifications induced by age or H diet, including increased whole body lean mass and lipid redistribution from the abdominal area, and normalized the chronic low-grade inflammation induced by H diet feeding; these effects may be mediated by increased metabolism of anti-inflammatory n-3 fatty acids from chia seed. These results suggest that chronic H diet feeding for 32 wk mimics the diet-induced cardiovascular and metabolic changes in middle age and that chia seed may serve as an alternative dietary strategy in the management of these changes.

Quercetin ameliorates cardiovascular, hepatic, and metabolic changes in diet-induced metabolic syndrome in rats

Metabolic syndrome is a risk factor for cardiovascular disease and nonalcoholic fatty liver disease (NAFLD). We investigated the responses to the flavonol, quercetin, in male Wistar rats (8-9 wk old) divided into 4 groups. Two groups were given either a corn starch-rich (C) or high-carbohydrate, high-fat (H) diet for 16 wk; the remaining 2 groups were given either a C or H diet for 8 wk followed by supplementation with 0.8 g/kg quercetin in the food for the following 8 wk (CQ and HQ, respectively). The H diet contained ~68% carbohydrates, mainly as fructose and sucrose, and ~24% fat from beef tallow; the C diet contained ~68% carbohydrates as polysaccharides and ~0.7% fat. Compared with the C rats, the H rats had greater body weight and abdominal obesity, dyslipidemia, higher systolic blood pressure, impaired glucose tolerance, cardiovascular remodeling, and NAFLD. The H rats had lower protein expressions of nuclear factor (erythroid-derived 2)-related factor-2 (Nrf2), heme oxygenase-1 (HO-1), and carnitine palmitoyltransferase 1 (CPT1) with greater expression of NF-κB in both the heart and the liver and less expression of caspase-3 in the liver than in C rats. HQ rats had higher expression of Nrf2, HO-1, and CPT1 and lower expression of NF-κB than H rats in both the heart and the liver. HQ rats had less abdominal fat and lower systolic blood pressure along with attenuation of changes in structure and function of the heart and the liver compared with H rats, although body weight and dyslipidemia did not differ between the H and HQ rats. Thus, quercetin treatment attenuated most of the symptoms of metabolic syndrome, including abdominal obesity, cardiovascular remodeling, and NAFLD, with the most likely mechanisms being decreases in oxidative stress and inflammation.

Ellagic acid attenuates high-carbohydrate, high-fat diet-induced metabolic syndrome in rats

BACKGROUND

Fruits and nuts may prevent or reverse common human health conditions such as obesity, diabetes and hypertension; together, these conditions are referred to as metabolic syndrome, an increasing problem. This study has investigated the responses to ellagic acid, present in many fruits and nuts, in a diet-induced rat model of metabolic syndrome.

METHODS

Eight- to nine-week-old male Wistar rats were divided into four groups for 16-week feeding with cornstarch diet (C), cornstarch diet supplemented with ellagic acid (CE), high-carbohydrate, high-fat diet (H) and high-carbohydrate, high-fat diet supplemented with ellagic acid (HE). CE and HE rats were given 0.8 g/kg ellagic acid in food from week 8 to 16 only. At the end of 16 weeks, cardiovascular, hepatic and metabolic parameters along with protein levels of Nrf2, NF-κB and CPT1 in the heart and the liver were characterised.

RESULTS

High-carbohydrate, high-fat diet-fed rats developed cardiovascular remodelling, impaired ventricular function, impaired glucose tolerance, non-alcoholic fatty liver disease with increased protein levels of NF-κB and decreased protein levels of Nrf2 and CPT1 in the heart and the liver. Ellagic acid attenuated these diet-induced symptoms of metabolic syndrome with normalisation of protein levels of Nrf2, NF-κB and CPT1.

CONCLUSIONS

Ellagic acid derived from nuts and fruits such as raspberries and pomegranates may provide a useful dietary supplement to decrease the characteristic changes in metabolism and in cardiac and hepatic structure and function induced by a high-carbohydrate, high-fat diet by suppressing oxidative stress and inflammation.

Coffee extract attenuates changes in cardiovascular and hepatic structure and function without decreasing obesity in high-carbohydrate, high-fat diet-fed male rats

Coffee, a rich source of natural products, including caffeine, chlorogenic acid, and diterpenoid alcohols, has been part of the human diet since the 15th century. In this study, we characterized the effects of Colombian coffee extract (CE), which contains high concentrations of caffeine and diterpenoids, on a rat model of human metabolic syndrome. The 8-9 wk old male Wistar rats were divided into four groups. Two groups of rats were fed a corn starch-rich diet whereas the other two groups were given a high-carbohydrate, high-fat diet with 25% fructose in drinking water for 16 wk. One group fed each diet was supplemented with 5% aqueous CE for the final 8 wk of this protocol. The corn starch diet contained ~68% carbohydrates mainly as polysaccharides, whereas the high-carbohydrate, high-fat diet contained ~68% carbohydrates mainly as fructose and sucrose together with 24% fat, mainly as saturated and monounsaturated fat from beef tallow. The high-carbohydrate, high-fat diet-fed rats showed the symptoms of metabolic syndrome leading to cardiovascular remodeling and nonalcoholic fatty liver disease. CE supplementation attenuated impairment in glucose tolerance, hypertension, cardiovascular remodeling, and nonalcoholic fatty liver disease without changing abdominal obesity and dyslipidemia. This study suggests that CE can attenuate diet-induced changes in the structure and function of the heart and the liver without changing the abdominal fat deposition.